In a known manner, the crankcase is connected to the air intake of the internal combustion engine via a separation device in order to continuously evacuate crankcase emissions and extract the suspended oil. This is known to the skilled person as the crankcase emission or blowby gas recycling system. Various means for separating oil from crankcase emissions are used in the prior art, among which are cyclones, baffles, centrifugal separators, static coalescers, and dynamic coalescers.
In the category of dynamic coalescers, the media used is typically the same as in static coalescers, but the filtering element comprising this medium is also rotated. These devices combine the advantages of the static coalescer and centrifugal separators: the efficiency is high due to the filtering medium and the pressure drop is reduced due to the centrifugal effect which contributes to evacuating the oil from the medium. This rotation makes it possible to use a more closed and therefore more efficient medium while maintaining an acceptable pressure drop. One should refer in particular to document FR 2 933 626, which describes such a device. The rotor element engaged in the inner space of the filtering element typically cooperates with one of the two flanges of the filtering element. However, the other flange may then be more likely to break due to the torsional forces (these forces tending to tear this flange from the filtering medium).
Another disadvantage of this type of separation device is that its construction is more complex, due to the mobility of the parts and the need for fluidtightness between the area upstream of the filtering element where the crankcase emissions circulate and the area downstream where the purified emissions circulate. Assembly on the drive shaft can also be difficult. This results in an additional cost, which limits the use of dynamic coalescers.